Air heater



NOV. 9, 1954 s BYSTRQM 2,693,941

AIR HEATER Filed April 12, 1951 2 Sheets-Sheet l AT TOHNE Y United States PatetitC) AIR HEATER Sigfred O. Bystrom, St. Paul, Minn. Application April 12, 1951, Serial No. 220,669 1 Claim. (Cl. 257-471) My invention relates to an improvement in heat saving apparatus and deals particularly with a device designed forinsertion into a smoke pipe leading from a furnace to a chimney and capable of extracting heat from the chimney gases.

It has long been recognized that much heat from a furnace or boiler is carried by gasses up the chimney. Various types of devices have been interposed in the flue connecting the furnace or boiler to the chimney for reducing the temperature of the exhaust gases and transferring the heat to the air. Some of these devices have been found objectionable due to the fact that the gases can not follow their normal path in escaping from the furnace to the chimney. The present device is designed to heat the air without greatly interfering with the natural flow of air or gas through the furnace.

An object of the present invention lies in the provision of a heat saving device incorporating a fan. A heat transfer structure is interposed in the flue connecting the furnace to the chimney. The fan is arranged to flow air through this heat transfer device and thereby to provide an eflicient heating of surrounding air.

A feature of the present invention resides in the provision of a heat saving device having a series of flues through which air may flow transversely of the path of the travel of the escaping gases from the furnace. These flues are elongated in form and are designed to permit gas to flow with a minimum of interference, but yet with a maximum of heat transfer. The flues are supported for rotation about a longitudinal axis so that the position thereof may be varied in a manner to increase or decrease heat transfer with a corresponding increase or decrease of draft interference.

Some furnaces are connected to chimneys which provide suflicient draft to draw the escaping gases through a tortuous passage. Other furnaces are connected to chimneys which provide relatively little draft eifect and which therefore would be ineffective to draw gases through a zig-zag path. The present invention deals with a heat saver having flues which are adjustable in position so that the direction of travel of the gases may be regulated to suit each individual installation.

A feature of the present invention resides in the provision of a heat saver having an outer casing and an inner casing spaced therefrom. The inner casing is preferably cylindrical in form. The smoke duct communicates with the interior of the inner casing. Thus the inner enclosure is normally filled with smoke and furnace gases. The ends of the inner chamber are rotatably supported within the inner shell. Air flues are supported by the rotatable ends of the inner shell. Thus the position of the air flues may be varied by rotating the inner shell ends.

A feature of the present invention lies in the provision of a double walled heat saver body including an outer shell and an inner shell. Smoke and heated gases communicate with the inner chamber. Air is drawn in through one end of the outer chamber and through the space between the chambers to the end opposite the inlet end. From this point the gases are blown through flues extending through the smoke filled inner chamber and through an outlet located at the same end of the body as the inlet. Thus the air is heated both by the outer walls of the inner receptacle and the flue walls of the flues passing through the inner chamber.

These and other objects and novel features of my 2,693,941 Patented Nov. 9, 1954 invention will be more clearly and fully set forth in the following specification and claim.

In the drawings forming a part of the specification: Figure 1 is a side elevation view of the heat saver when the same is interposed in a vertical smoke pipe and would comprise a plan view of the heat saver if placed in a horizontal pipe.

Figure 2 is an end elevation view of the heat saver.

Figure 3 is an end view of the opposite end of the heat saver from that illustrated in Figure 2.

Figure 4 is a longitudinal sectional view through the heat saver, the position of the section being indicated by the line 44 of Figure 3.

Figure 5 is a transverse section through the heat saver, the position of the section being indicated by the line 55 of Figure 4.

The construction of the heat saver is in general best illustrated in the sectional views showing the relationship between the various parts. In general the heat saver is indicated by the letter A. The heat saver includes an outer encircling shell 10 which is shown as being cylindrical in form. At one end this shell 10 is connected to a ring shaped cap 11 having perforations 12 therethrough. The shell 10 and cap 11 are connected by metal screws 13 or other suitable means. The other end of the shell 10 is connected by metal screws 14 or other suitable means to a cap or end closure 15. This end closure 15 includes tapering walls 16 and a closed end panel 17. In other words, this end closure 15 is pan shaped in form.

An inner sleeve 19 or inner shell is supported within the outer shell 10 in spaced relation thereto. The inner sleeve is cylindrical in form and is connected at one end to the cap 11 by metal screws 20 or other suitable fastening means. A reinforcing ring 21 of T-shaped cross section includes an outer peripheral flange 22 and an inwardly projecting flanges 23. The metal screws 20 preferably extend into this flange 22 of this ring 21 to anchor these parts together. An outer ring 24 of angular cross section overlies the end of the cap 11 and is also fastened in place by the screws 20. This outer ring 24 is right angular in cross section and holds in place a screen 25 or other foraminous plate through which air may flow. This screen 25 is clamped between the angularly shaped ring 24 and the reinforcing ring 21.

A second reinforcing ring 26 is anchored within the opposite end of the inner shell 19 by metal screws 27 or other suitable fastening means. These screws 27 also anchor in place an inner bafile 29. This baffle is pan shaped in form and is somewhat similar in outline to the end closure 15, but is of smaller diameter so as to be continuously spaced therefrom. The baffle 19 includes an end wall 30 which is anchored to the end wall 17 of the closure 15 by bolts 31 which support spacing sleeves 32. The bolts 31 connect the members 15 and 29 together but hold the same in longitudinally spaced relation. An enlarged aperture 33 is provided in the end wall of the baflle 29 to permit air to flow therethrough.

A smoke inlet pipe adapter 34 extends through a suitable hole in the outer shell 10 and is secured to the inner shell 19 as best illustrated in Figures 4 and 5 of the drawings. The adapter 34 is designed for connection with a furnace pipe through which gases pass from the furnace. A similar adapter 36 extends through the shell 10 in diametrically opposed relation to the adapter 34 and is anchored to the inner shell 19. The adapter 36 is designed to connect with a pipe communicating with the chimney. In other words, the inner shell is subject to heated gases entering through the adapter 34 and leaving through the adapter 36 en route to the chimney.

A pair of end panels 37 and 39 are provided at opposite ends of the inner shell 19 to close the ends of this inner shell. The panel 37 encircles the lateral flange of the reinforcing ring 26 and is rotatably supported thereby. A gasket may be interposed between these parts to prevent the leakage of gas. A panel 39 is similarly supported by the inner end of the lateral flange 22 of the reinforcing ring 21. Thus the two end panels may rotate about the axis of the sleeve 19.

A series of flues are supported by the end panels 37 and 39. The center of these flues is elongated in cross section-and includes a relatively narrow-end-portion-40- which includes parallel sides 41 and 42 and a rounded end 43. Near the center of the structure the sides 41 and 42 diverge apart as indicated .at'44 and-45.,respectivgly,6 and are provided with a rounded connecting en .4

A pair of flues 47 and 49 are provided on -,opposite sides of the center flue .40 spaced, from the flattenedend of the flue. The flues 47 and 49 are generally triangular in shape. The flue 47 includes a. flat side 5.0 :generally parallel to and spaced from theflatside 41 of the flue 40. An outwardly diverging side 51 connects the. side 50 with the outer side 52 of the flue.

The flue 49 is shaped similarly to the flue. 47 and includes a flat side 53 in parallelspaced relation to the side 42 of the flue 40. An outwardly diverging side 54 and an outer side 55 complete the section of the flue 49.

It will be noted that the vertical ,depth of the flue 40 as viewed in Figure is equal to or slightly greater than the distance betweenithe flatsides 50 and 53 of the flues 47 and 49. It will also be noted that the total width of the flues 40, 47, and 49 is substantially equal to the diameter of the inletiand outlet adapters 34 and 36. When the flues are in the position indicated in Figure 5, the gas must travel a tortuous path in order to flow from the adapter 34 to the adapter 36. However, when these fines are turned at right angles the gas may pass almost, but notquite, on a straight line from one adapter to the other, thus providing a minimum of resistance while yetproviding a large heat transfer area.

As will be seen a series of angularlyspaced brackets 56 are anchored to the enclosure-15 to project outwardly therefrom. A motor 57 is supported by these brackets 56. As indicated in Figure 2 of the drawings a clamping ring is divided into several parts 59 equal in number to the brackets 56 and these parts 59 have a center por- .tion which encircles the motor 57 and have outwardly directed ears 60 at each end thereof. The brackets 57 extend between the spaced pairs of ears 60 and mounting bolts 61 of any suitable type extend through the ears 6t? and through tubularly bent ends .62 of the brackets 56 to hold these parts assembled. A sleeve 63 of rubber or other suitable cushioning material is preferably provided within each tubularbracket end 62-to cushion the mounting.

As will be seen when the clamping bolts 61 are tightened orsecured in place the motor 57 will be supported with its axis aligned with-theaxis of the sleeves and 19. A motor shaft 64 projects through an aperture 65 in the end 17 of the closure and through the aperture 33. A fan 66 is supported on the-motor shaft. This fan drives air through the flues 40, 47 and 49.

The operation of the device is believed obvious from the foregoing description. The apparatus may be placed either in a vertical section of-pipe, a horizontal ,section thereof, or an inclined section of pipe. Thepipe leading to the furnace is connected to the adapter 34 While the adapter 36 is connected to the chimney pipe. Thus the heated gases may flow throughthe interior of the inner shell 19 between the end panels 37 and 39 and about the flues 40, 47 and 49.

Some furnaces are connectedto their chimneys in such a Way that there is a relatively strong tortuous draft. As a result in these installations the gases may be-caused-to flow past the flues when arranged at right angles to the smoke passage. When arranged in this way a maximum amount of heat is transferred to the fines and to the encircling shell 19. In other furnace installations there is a relatively light draft provided and under all conditions the draft might not be sufficient to draw the smoke and gases past the tines. The fiues may be rotated so that the longitudinal edges 41 and 42 extend substantially parallel to the normal smoke travel direction,v thereby minimizing the deflection of the smoke and gases. Any angle between the extreme positions may be employed to suit each individual installation. The flue position is preferably set under minimum draft conditions so thateven, under minimum draft the smoke will pass through the heat saving device.

Air is drawn inwardly through the openings 12 in the cap 11 at one end of the outer shell 10. These gases are heated by contact with the outer surface. of the inner shell 19 and. by the surfaces of the adapters 34 and 36. The air.is drawn between the outer and inner shells and between the closure 15 and the inner baffle 29. This air is then pulled through the aperture 33by the fan 66 and is blown through the lines 40, 47 and 49 and out through the outlet screen 25. Thus the air travels first in .one direction and then in the other in passing through the apparatus.

In accordance With the patent statutes, I have described the principles of constructionand operation of my heat saving, apparatus, and while Ihave endeavored to set forth the best embodiment thereof, I desireto have itunderstood. that obvious changes .may be made within the scope of the following claim without departing from the .spirit of my invention.

I-claim:

A heat-saver including a generally cylindrical body, a .pair of end panels rotatably supported within said body and forming end closures therefor, a series of .flues supported by said end panels and forming air passages through thespace between said panels, said flues' being elongated in'cross sectionwand arranged in substantially parallel spaced relation,.opposed inlet and outlet passages in said body communicating with the spacebetween said end panels, saidflues being rotatable from a position with the longitudinal axis of the section substantially in the path of flow of gases from said inlet to said outlet to a position at right angles thereto, an ,outer shell encircling said body, an airinlet at one end of said outer shell, and means near the otherend of the. outer shell gor forcing air between said shells and then through said .ues.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,108,033 Cooper Feb. 15, 1938 2,311,984 Guild Feb.. 23, 1943 2,414,829 McCollum Jan-28; 1947 2,421,37 Budlane June ,3, 1947 2,575,894 Shireman Nov. 20, 1951 FOREIGN PATENTS Number Country Date 622,899 Great Britain May 9, 1949 

